Seagate Technology will demonstrate HAMR, a technology it's counting on to fit more data onto hard disk drives, at the Ceatec show this week.

HAMR (heat-assisted magnetic recording) uses heat delivered by a laser to help write data onto the surface of HDDs (hard disk drives). This allows drives to write bits of data closer together so more information can be stored in a given amount of space on a disk platter. At this week's huge electronics show in Tokyo, in partner TDK's booth, Seagate will demonstrate HAMR on a 2.5-inch, 10,000-rpm HDD designed for enterprise blade servers.

Seagate expects to start selling HAMR drives in 2016, Chief Technology Officer Mark Re said. The technology, which other HDD vendors are also developing, has been in the works since the middle of the past decade. But that's not very long for new hard-drive technologies, Re said, citing more than 10 years of development for NAND flash.

Conventional HDDs are expected to run into a wall on data density about the time manufacturers have reached about 1Tbit per square inch, per platter. (Current drives pack in about 750Gbits per inch.) Hard drives store data by changing the magnetic polarity of cells on the disk, and smaller cells are more likely to turn unstable and change polarity. Cells' ability to hold the charge they've been set with is called coercivity, and HAMR is one technique to increase it, IDC analyst John Rydning said.

The looming limit applies to how densely bits can be written to disk at normal temperatures. With HAMR, the write head on the HDD heats up the area where data is being written, so Seagate can use a different kind of disk media with higher coercivity.

Seagate expects the first HAMR drives to break through the 1Tbit ceiling, and later generations can keep getting more dense until they reach about 5Tbits per inch, Re said. By 2020, it will make possible a 20TB hard drive, Seagate believes.

HDDs have to get more dense so users can continue to economically store the growing volumes of data they are creating and accumulating, IDC's Rydning said. The problem is most acute in enterprises, which store a lot of data that doesn't need to be used immediately, he said. In addition, growing density should help HDDs keep their cost-per-byte advantage over solid-state storage, though the growth of solid-state is being driven by a need for speed, not density, he said.

The density of HDDs has already grown many times over, which is why storing 4TB only takes one drive today, versus eight or more drives just a few years ago. More data on fewer drives means lower cost, heat and power consumption, Rydning said.

When all costs are factored in, Seagate expects the cost of HAMR drives to work out about the same as today's HDDs, Re said. They won't significantly increase power consumption either, because the added heating mechanism only consumes tens of milliwatts of additional power, Re said.

The Ceatec demonstration of HAMR won't be the first, even from Seagate, which claims no other vendor has shown the technology in a hard drive. But Ceatec may be the biggest stage yet for HAMR.

Seagate partly wants to reassure anyone worried about the technology, which has had a long development cycle, Rydning said.

"They're trying to ward off the skeptics," he said. "The technology is very, very difficult, and there has been a lot of skepticism if it will ever make it into commercial products." The consensus in the HDD industry seems to be that HAMR won't ship before 2017, he said.

Among the challenges in developing HAMR have been attaching and aligning a semiconductor diode laser to an HDD write head and implementing near-field optics to deliver the heat, Seagate's Re said. Near-field optics isn't new, but HDDs would be the largest volume implementation yet of the technology, he said. TDK made some components for the Seagate-developed recording head that will be used in the demonstration, he said.